/*      $FreeBSD: src/sys/netinet6/in6_rmx.c,v 1.1.2.4 2004/10/06 02:35:17 suz Exp $    */
/*      $DragonFly: src/sys/netinet6/in6_rmx.c,v 1.15 2006/12/22 23:57:53 swildner Exp $        */
/*      $KAME: in6_rmx.c,v 1.11 2001/07/26 06:53:16 jinmei Exp $        */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright 1994, 1995 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

/*
 * This code does two things necessary for the enhanced TCP metrics to
 * function in a useful manner:
 *  1) It marks all non-host routes as `cloning', thus ensuring that
 *     every actual reference to such a route actually gets turned
 *     into a reference to a host route to the specific destination
 *     requested.
 *  2) When such routes lose all their references, it arranges for them
 *     to be deleted in some random collection of circumstances, so that
 *     a large quantity of stale routing data is not kept in kernel memory
 *     indefinitely.  See in6_rtqtimo() below for the exact mechanism.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/mbuf.h>
#include <sys/syslog.h>
#include <sys/globaldata.h>
#include <sys/thread2.h>

#include <net/if.h>
#include <net/route.h>
#include <net/netisr2.h>
#include <net/netmsg2.h>
#include <netinet/in.h>
#include <netinet/ip_var.h>
#include <netinet/in_var.h>

#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>

#include <netinet/icmp6.h>
#include <netinet6/nd6.h>

#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>

struct in6_rttimo_ctx {
        struct callout          timo_ch;
        struct netmsg_base      timo_nmsg;
        struct radix_node_head  *timo_rnh;
} __cachealign;

static struct in6_rttimo_ctx    in6_rtqtimo_ctx[MAXCPU];
static struct in6_rttimo_ctx    in6_mtutimo_ctx[MAXCPU];

extern int      in6_inithead (void **head, int off);

#define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */

/*
 * Do what we need to do when inserting a route.
 */
static struct radix_node *
in6_addroute(const void *key, const void *mask, struct radix_node_head *head,
             struct radix_node *nodes)
{
        struct rtentry *rt = (struct rtentry *)nodes;
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)rt_key(rt);
        struct radix_node *ret;

        /*
         * For IPv6, all unicast non-host routes are automatically cloning.
         */
        if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
                rt->rt_flags |= RTF_MULTICAST;

        if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) {
                rt->rt_flags |= RTF_PRCLONING;
        }

        /*
         * A little bit of help for both IPv6 output and input:
         *   For local addresses, we make sure that RTF_LOCAL is set,
         *   with the thought that this might one day be used to speed up
         *   ip_input().
         *
         * We also mark routes to multicast addresses as such, because
         * it's easy to do and might be useful (but this is much more
         * dubious since it's so easy to inspect the address).  (This
         * is done above.)
         *
         * XXX
         * should elaborate the code.
         */
        if (rt->rt_flags & RTF_HOST) {
                if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)
                                        ->sin6_addr,
                                       &sin6->sin6_addr)) {
                        rt->rt_flags |= RTF_LOCAL;
                }
        }

        if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) &&
            rt->rt_ifp != NULL)
                rt->rt_rmx.rmx_mtu = IN6_LINKMTU(rt->rt_ifp);

        ret = rn_addroute(key, mask, head, nodes);
        if (ret == NULL && rt->rt_flags & RTF_HOST) {
                struct rtentry *rt2;

                /*
                 * We are trying to add a host route, but can't.
                 * Find out if it is because of an
                 * ARP entry and delete it if so.
                 */
                rt2 = rtpurelookup((struct sockaddr *)sin6);
                if (rt2 != NULL) {
                        --rt2->rt_refcnt;
                        if (rt2->rt_flags & RTF_LLINFO &&
                            rt2->rt_flags & RTF_HOST &&
                            rt2->rt_gateway &&
                            rt2->rt_gateway->sa_family == AF_LINK) {
                                rtrequest(RTM_DELETE, rt_key(rt2),
                                          rt2->rt_gateway, rt_mask(rt2),
                                          rt2->rt_flags, NULL);
                                ret = rn_addroute(key, mask, head, nodes);
                        }
                }
        } else if (ret == NULL && rt->rt_flags & RTF_CLONING) {
                struct rtentry *rt2;

                /*
                 * We are trying to add a net route, but can't.
                 * The following case should be allowed, so we'll make a
                 * special check for this:
                 *      Two IPv6 addresses with the same prefix is assigned
                 *      to a single interrface.
                 *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
                 *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
                 *      In this case, (*1) and (*2) want to add the same
                 *      net route entry, 3ffe:0501:: -> if0.
                 *      This case should not raise an error.
                 */
                rt2 = rtpurelookup((struct sockaddr *)sin6);
                if (rt2 != NULL) {
                        if ((rt2->rt_flags & (RTF_CLONING|RTF_HOST|RTF_GATEWAY))
                                        == RTF_CLONING &&
                            rt2->rt_gateway &&
                            rt2->rt_gateway->sa_family == AF_LINK &&
                            rt2->rt_ifp == rt->rt_ifp) {
                                ret = rt2->rt_nodes;
                        }
                        --rt2->rt_refcnt;
                }
        }
        return ret;
}

/*
 * This code is the inverse of in6_clsroute: on first reference, if we
 * were managing the route, stop doing so and set the expiration timer
 * back off again.
 */
static struct radix_node *
in6_matchroute(const void *key, struct radix_node_head *head)
{
        struct radix_node *rn = rn_match(key, head);
        struct rtentry *rt = (struct rtentry *)rn;

        if (rt != NULL && rt->rt_refcnt == 0) { /* this is first reference */
                if (rt->rt_flags & RTPRF_OURS) {
                        rt->rt_flags &= ~RTPRF_OURS;
                        rt->rt_rmx.rmx_expire = 0;
                }
        }
        return rn;
}

SYSCTL_DECL(_net_inet6_ip6);

static int rtq_reallyold = 60*60;
        /* one hour is ``really old'' */
SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire,
    CTLFLAG_RW, &rtq_reallyold , 0, "Default expiration time on cloned routes");

static int rtq_minreallyold = 10;
        /* never automatically crank down to less */
SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
    &rtq_minreallyold , 0, "Minimum time to attempt to hold onto cloned routes");

static int rtq_toomany = 128;
        /* 128 cached routes is ``too many'' */
SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache,
    CTLFLAG_RW, &rtq_toomany , 0, "Upper limit on cloned routes");


/*
 * On last reference drop, mark the route as belong to us so that it can be
 * timed out.
 */
static void
in6_clsroute(struct radix_node *rn, struct radix_node_head *head)
{
        struct rtentry *rt = (struct rtentry *)rn;

        if (!(rt->rt_flags & RTF_UP))
                return;         /* prophylactic measures */

        if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
                return;

        if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
                return;

        /*
         * As requested by David Greenman:
         * If rtq_reallyold is 0, just delete the route without
         * waiting for a timeout cycle to kill it.
         */
        if (rtq_reallyold != 0) {
                rt->rt_flags |= RTPRF_OURS;
                rt->rt_rmx.rmx_expire = time_uptime + rtq_reallyold;
        } else {
                /*
                 * Remove route from the radix tree, but defer deallocation
                 * until we return to rtfree().
                 */
                rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway, rt_mask(rt),
                          rt->rt_flags, &rt);
        }
}

struct rtqk_arg {
        struct radix_node_head *rnh;
        int mode;
        int updating;
        int draining;
        int killed;
        int found;
        time_t nextstop;
};

/*
 * Get rid of old routes.  When draining, this deletes everything, even when
 * the timeout is not expired yet.  When updating, this makes sure that
 * nothing has a timeout longer than the current value of rtq_reallyold.
 */
static int
in6_rtqkill(struct radix_node *rn, void *rock)
{
        struct rtqk_arg *ap = rock;
        struct rtentry *rt = (struct rtentry *)rn;
        int err;

        if (rt->rt_flags & RTPRF_OURS) {
                ap->found++;

                if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
                        if (rt->rt_refcnt > 0)
                                panic("rtqkill route really not free");

                        err = rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                        rt_mask(rt), rt->rt_flags, NULL);
                        if (err)
                                log(LOG_WARNING, "in6_rtqkill: error %d", err);
                        else
                                ap->killed++;
                } else {
                        if (ap->updating &&
                            (rt->rt_rmx.rmx_expire - time_uptime >
                             rtq_reallyold)) {
                                rt->rt_rmx.rmx_expire =
                                    time_uptime + rtq_reallyold;
                        }
                        ap->nextstop = lmin(ap->nextstop,
                                            rt->rt_rmx.rmx_expire);
                }
        }

        return 0;
}

#define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
static int rtq_timeout = RTQ_TIMEOUT;

static void
in6_rtqtimo(void *arg __unused)
{
        int cpuid = mycpuid;
        struct lwkt_msg *lmsg = &in6_rtqtimo_ctx[cpuid].timo_nmsg.lmsg;

        crit_enter();
        if (lmsg->ms_flags & MSGF_DONE)
                lwkt_sendmsg_oncpu(netisr_cpuport(cpuid), lmsg);
        crit_exit();
}

static void
in6_rtqtimo_dispatch(netmsg_t nmsg)
{
        struct in6_rttimo_ctx *ctx = &in6_rtqtimo_ctx[mycpuid];
        struct radix_node_head *rnh = ctx->timo_rnh;
        struct rtqk_arg arg;
        struct timeval atv;
        static time_t last_adjusted_timeout = 0;

        ASSERT_NETISR_NCPUS(mycpuid);

        /* Reply ASAP */
        crit_enter();
        lwkt_replymsg(&nmsg->lmsg, 0);
        crit_exit();

        arg.found = arg.killed = 0;
        arg.rnh = rnh;
        arg.nextstop = time_uptime + rtq_timeout;
        arg.draining = arg.updating = 0;
        rnh->rnh_walktree(rnh, in6_rtqkill, &arg);

        /*
         * Attempt to be somewhat dynamic about this:
         * If there are ``too many'' routes sitting around taking up space,
         * then crank down the timeout, and see if we can't make some more
         * go away.  However, we make sure that we will never adjust more
         * than once in rtq_timeout seconds, to keep from cranking down too
         * hard.
         */
        if ((arg.found - arg.killed > rtq_toomany)
           && (int)(time_uptime - last_adjusted_timeout) >= rtq_timeout
           && rtq_reallyold > rtq_minreallyold) {
                rtq_reallyold = 2*rtq_reallyold / 3;
                if (rtq_reallyold < rtq_minreallyold) {
                        rtq_reallyold = rtq_minreallyold;
                }

                last_adjusted_timeout = time_uptime;
#ifdef DIAGNOSTIC
                log(LOG_DEBUG, "in6_rtqtimo: adjusted rtq_reallyold to %d",
                    rtq_reallyold);
#endif
                arg.found = arg.killed = 0;
                arg.updating = 1;
                rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
        }

        atv.tv_usec = 0;
        atv.tv_sec = arg.nextstop - time_uptime;
        if ((int)atv.tv_sec < 1) {              /* time shift safety */
                atv.tv_sec = 1;
                arg.nextstop = time_uptime + atv.tv_sec;
        }
        if ((int)atv.tv_sec > rtq_timeout) {    /* time shift safety */
                atv.tv_sec = rtq_timeout;
                arg.nextstop = time_uptime + atv.tv_sec;
        }
        callout_reset(&ctx->timo_ch, tvtohz_high(&atv), in6_rtqtimo, NULL);
}

/*
 * Age old PMTUs.
 */
struct mtuex_arg {
        struct radix_node_head *rnh;
        time_t nextstop;
};

static int
in6_mtuexpire(struct radix_node *rn, void *rock)
{
        struct rtentry *rt = (struct rtentry *)rn;
        struct mtuex_arg *ap = rock;

        /* sanity */
        if (!rt)
                panic("rt == NULL in in6_mtuexpire");

        if (rt->rt_rmx.rmx_expire && !(rt->rt_flags & RTF_PROBEMTU)) {
                if (rt->rt_rmx.rmx_expire <= time_uptime) {
                        rt->rt_flags |= RTF_PROBEMTU;
                } else {
                        ap->nextstop = lmin(ap->nextstop,
                                        rt->rt_rmx.rmx_expire);
                }
        }

        return 0;
}

#define MTUTIMO_DEFAULT (60*1)

static void
in6_mtutimo(void *arg __unused)
{
        int cpuid = mycpuid;
        struct lwkt_msg *lmsg = &in6_mtutimo_ctx[cpuid].timo_nmsg.lmsg;

        crit_enter();
        if (lmsg->ms_flags & MSGF_DONE)
                lwkt_sendmsg_oncpu(netisr_cpuport(cpuid), lmsg);
        crit_exit();
}

static void
in6_mtutimo_dispatch(netmsg_t nmsg)
{
        struct in6_rttimo_ctx *ctx = &in6_mtutimo_ctx[mycpuid];
        struct radix_node_head *rnh = ctx->timo_rnh;
        struct mtuex_arg arg;
        struct timeval atv;

        ASSERT_NETISR_NCPUS(mycpuid);

        /* Reply ASAP */
        crit_enter();
        lwkt_replymsg(&nmsg->lmsg, 0);
        crit_exit();

        arg.rnh = rnh;
        arg.nextstop = time_uptime + MTUTIMO_DEFAULT;
        rnh->rnh_walktree(rnh, in6_mtuexpire, &arg);

        atv.tv_usec = 0;
        atv.tv_sec = arg.nextstop - time_uptime;
        if ((int)atv.tv_sec < 1) {              /* time shift safety */
                atv.tv_sec = 1;
                arg.nextstop = time_uptime + atv.tv_sec;
        }
        if ((int)atv.tv_sec > rtq_timeout) {    /* time shift safety */
                atv.tv_sec = rtq_timeout;
                arg.nextstop = time_uptime + atv.tv_sec;
        }
        callout_reset(&ctx->timo_ch, tvtohz_high(&atv), in6_mtutimo, NULL);
}

#if 0
void
in6_rtqdrain(void)
{
        struct radix_node_head *rnh = rt_tables[mycpuid][AF_INET6];
        struct rtqk_arg arg;

        arg.found = arg.killed = 0;
        arg.rnh = rnh;
        arg.nextstop = 0;
        arg.draining = 1;
        arg.updating = 0;
        crit_enter();
        rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
        crit_exit();
}
#endif

/*
 * Initialize our routing tree.
 */
int
in6_inithead(void **head, int off)
{
        struct radix_node_head *rnh;
        struct in6_rttimo_ctx *ctx;
        int cpuid = mycpuid;

        rnh = *head;
        KKASSERT(rnh == rt_tables[cpuid][AF_INET6]);

        if (!rn_inithead(&rnh, rn_cpumaskhead(cpuid), off))
                return 0;

        *head = rnh;
        rnh->rnh_addaddr = in6_addroute;
        rnh->rnh_matchaddr = in6_matchroute;
        rnh->rnh_close = in6_clsroute;

        ctx = &in6_rtqtimo_ctx[cpuid];
        ctx->timo_rnh = rnh;
        callout_init_mp(&ctx->timo_ch);
        netmsg_init(&ctx->timo_nmsg, NULL, &netisr_adone_rport, MSGF_PRIORITY,
            in6_rtqtimo_dispatch);

        ctx = &in6_mtutimo_ctx[cpuid];
        ctx->timo_rnh = rnh;
        callout_init_mp(&ctx->timo_ch);
        netmsg_init(&ctx->timo_nmsg, NULL, &netisr_adone_rport, MSGF_PRIORITY,
            in6_mtutimo_dispatch);

        in6_rtqtimo(NULL);      /* kick off timeout first time */
        in6_mtutimo(NULL);      /* kick off timeout first time */

        return 1;
}